The present invention relates to an information transmission arrangement using frequency modulation, the arrangement being formed by at least one sending unit comprising:
a sending circuit built up around an oscillator having a frequency control input, for sending an information transmission wave, PA0 a frequency control circuit to supply to said control input signals having frequency-variation amplitudes and variation slopes depending on the information to be transmitted, PA0 a receiving circuit to receive said wave and produce a signal to be demodulated, PA0 a demodulation circuit to receive the signal to be demodulated and recover said information for supply to a user circuit.
and at least one receiving unit comprising:
Such arrangements are well known. For example, on this subject the reader be referred to the article by G. DAVID et al. entitled "Transmission radioelectrique au moyen d'une modulation lineaire en frequence" published in the journal L'ONDE ELECTRIQUE, March 1971, Vol. 51, Fascicle 3, pp. 233-242.
In this known arrangement, the information constituted by bits having the values "1" and "0" is transmitted by assigning slopes having the value "p" to the "1" bits and slopes having the value "-p" to the "0" bits.
The above article deals with all the advantages of this type of transmission link: more specifically, resistance to jamming and improvement of the signal-to-noise ratio at the receiving end when using correlation techniques. However, with an arrangement of this type one is confronted with disturbing effects produced at each discontinuity of the frequency occurring abruptly between the successive bits having the same value.